Apparatus for applying ink to holes

ABSTRACT

Material is applied to holes in a workpiece by transfer pins. The material is first introduced into holes in a template arranged in a pattern corresponding to the holes in the workpiece. Free ends of the transfer pins are then moved through the holes in the template to transfer the material to the holes in the workpiece. The material may then be pulled through the holes by a vacuum.

United States Patent [56] References Cited UNITED STATES PATENTSInventors Joseph C. Mallia Colonia;

John C. Walz, Bloomfield. both of. NJ.

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Primary Examiner-John P. Mclntosh Attorneys-H. J. Winegar, R. P. Millerand W. L. Williamson [54] gg INK To HOLES ABSTRACT: Material is appliedto holes in a workpiece by transfer pins. The material is firstintroduced into holes in a template arranged in a pattern correspondingto the holes in the workpiece. Free ends of the transfer pins are thenmoved through the holes in the template to transfer the material to theholes in the workpiece. The material may then be pulled through theholes by a vacuum.

32 t. O 40 5 Ru C1 sll 0 B l- 8 m M m Un .mF ll 0 55 [l PATENTEU SEP]4191:

snznuoF s APPARATUS FOR APPLYING INK TO HOLES BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to apparatusfor applying material to holes formed in a workpiece, and moreparticularly, to apparatus for applying adhesive catalytic ink to theperiphery and walls of holes formed in a printed wiring board.

In manufacturing printed wiring assemblies on a production basis, themaking of reliable electrical connections between the printed wiring andthe component lead wires which extend through the holes in the printedwiring board has been a continuing source of difficulty. This isparticularly true when the printed wiring is produced by the successivesteps of applying catalytic ink through the silk-screening technique andthen plating copper onto the ink. Where the hole has a rounded orchamfered edge, it has been found that silk screening does not in allinstances give a well-controlled coating of ink to the periphery of thehole. As a result, special techniques have been developed for treatingholes, so that both the periphery and a portion of the walls of theholes will be adequately covered.

2. Description of the Prior Art One method used to coat the peripheryand walls of the holes involves the application of ink onto the topsurface of the printed wiring board using an array of resilientlymounted pins to which ink has been applied. The array has a patterncorresponding to that of the holes in the printed wiring board, and thetips of the pins are usually rounded or tapered to conform to the edgesof the holes. This technique has a disadvantage in that it is difficultto control accurately the amount of ink which adheres to the applicatortip; furthermore, when the ink is fairly viscous, some of the ink ispulled upward when the applicator is raised away from the hole and thisink will occasionally fall back unevenly about the hole.

Another technique which has been taught for applying material to theperiphery of holes involves spreading the material across the surface ofthe printed wiring board, and then removing the excess using a squeegeeso that only the quantity which was introduced into the holes remains.This technique is suggested primarily for use with nonconducting solderresist material. It would be disadvantageous for use with catalyticadhesive ink since even minute traces of ink remaining on the surface ofthe board would result in copper deposition and possible high leakagebetween the printed wiring lines.

Other apparatus previously utilized or taught for applying ink to theperiphery and walls of holes has involved a number of successive stepsby the operator, has not provided optimum control of the amount of inkapplied, or has involved apparatus not readily suited to high productionrates.

SUMMARY OF THE INVENTION It is an object of this invention to provide anapparatus for applying controlled quantities of adhesive material toholes formed in a workpiece.

Another object of this invention is to provide an apparatus for applyingmaterial that aligns the material applying elements accurately withrespect to the holes in the workpiece.

A further object is to provide means for applying material which willnot contaminate the area surrounding the desired application.

With these and other objects in view, this invention contemplatesproviding a template having holes therein for receiving material andfacilities for displacing transfer pins through the holes and into closeproximity with a workpiece to transfer the material from the holes inthe template to predetermined holes in the workpiece.

BRIEF DESCRIPTION OF THE DRAWING The invention will be more clearlyunderstood by reference to the following detailed description of anembodiment thereof, in conjunction with the accompanying drawing, inwhich:

FIG. I is a perspective view of an apparatus for applying ink to holesin a printed wiring board, in the position for loading and unloading, asviewed from the upper side rear;

FIG. 2 is an enlarged cross section of the printing fixture assemblyportion of the apparatus shown in FIG. 1;

FIGS. 3 and 3a are enlarged cross sections of a portion of FIG. 2showing the pins which transfer ink, after the ink has been applied tothe pin and then as the ink is being applied to the printed wiringboard; FIG. 4 is a side elevation of the apparatus shown in FIG. 1,partially cut away to show the cam slide and clutch tripper mechanisms;

FIG. 5 is a plan view of the apparatus shown in FIG. 1;

FIG. 6 is an enlarged perspective view of a squeegee assembly used as anink applicator in the apparatus shown in FIG. 1;

FIG. 7 is a front elevation of the apparatus shown in FIG. I; and

FIG. 8 is an enlarged cross section of the shaft and intermittent clutchassembly for the apparatus shown in FIG. 1.

DETAILED DESCRIPTION Referring now to FIG. 1, there is shown anembodiment of the invention for applying a viscous adhesive catalyticink to the periphery and walls of holes in printed wiring boards,especially suited to mass production operations requiring minimum setuptime, This apparatus comprises a frame assembly 50 on which is mounted adriving motor 7 connected to an intermittent clutch assembly 120, foroperating the apparatus through a slide cam assembly 150 and pivot arms178l78. A workpiece 40 (FIG. 2) is inserted horizontally into a slot ina reciprocable carriage assembly 70 used as a workpiece holder. Thepivot arms l78l78 are connected to the carriage assembly 70 to move itfrom the loading position shown to a transfer or printing position. Inthe printing position, the workpiece is adjacent a printing fixtureassembly 10 having holes formed therein in a pattern corresponding tothe holes formed in the workpiece.

A squeegee assembly mounted on the carriage assembly 70 contains asupply of adhesive catalytic ink to be applied. As the carriage assembly70 moves, the ink is introduced into the holes of the printing fixtureassembly 10. When the carriage is in the printing position, movable pinswithin the printing fixture assembly are raised through the holes by themotion of a slide cam assembly to apply the ink introduced therein tothe workpiece. A vacuum nozzle 200 pulls air through the holes of theworkpiece to distribute the ink within the holes.

More particularly, the printing fixture assembly 10 shown in FIG. 2includes a horizontally disposed flat rectangular printing plate 11,used as a template, having chamfered upper edges 12 and 13 at its frontand rear ends and having a plurality of holes 14-14 arranged in apattern identical to the pattern of the holes in the workpiece which areto be imprinted. A stud 16 is rigidly fixed to the printing plate 11near each corner, and has a bearing surface 17 whose axis is parallel tothe axis of the other studs and essentially perpendicular to theprinting plate 11. Each stud 16 receives a slidably fitted bearingsleeve 18 which is tightly fitted in a bushing 19. Each bushing 19 ismounted in a movable lower plate 21 so that the lower plate ismaintained parallel to the printing plate 11 but vertically movablerelative thereto. A flat washer 22 is attached by a lockwasher 23 andretaining screw 24 at the lower end of each stud 16 to act as a stop forthe bushing 19. A compression spring 25, located about each of the studs16 and bushings 19, engages the printing plate 11 and the movable lowerplate 21 to hold the bushing against the stop,

A pin-retaining plate 27, having a plurality of holes 2828 arranged in apattern identical to the holes l414, is attached above but separatedfrom the movable lower plate 21 by a spacer 29 located therebetween, andis maintained in accurate alignment with the movable lower plate bydowel pins 31-31. A plurality of transfer pins 33-33, each pin having ahead 34 at its lower end, are slidably fitted in the holes 28-28, theupper end of each pin being slidably fitted in the corresponding hole 14of the printing plate 11. The head 34 of each pin 33 is within a recess36 of the spacer 29, and is pressed lightly up against the lower surfaceof the pin-retaining plate 27 by a resilient material 37 located in therecess. The pins 33-33 are of such length that the upper end of each pinis slightly below the upper surface of the printing plate 11, as mostclearly shown in FIG. 3, when the bushings 19-19 are against their flatwasher 22. The upper end of each pin 33 and the walls of thecorresponding hole 14 define a cavity into which ink 42 can beintroduced, see FIG. 3.

In this manner, when material is introduced into the holes in thetemplate so as to fill each such hole, an accurately controlled quantityof the material is provided which will then be transferred by the pinsto the workpiece, as seen in FIG. 3a Further, the use of relatively longmaterial transfer pins laterally supported at each end provides precisealignment of the pins and protects them from bending caused byaccidental contact during normal use.

As shown in FIGS. 4 and 5, the frame assembly 50 includes a base plate51 to which are attached two parallel vertical sideplates 52 and S3. Afront mounting block 54 and rear mounting block 55, fastenedtransversely to the sideplates and extending beyond each side of theupper edges thereof, receive a pair of longitudinally extending parallelguide rods 57-57 on which the carriage assembly 70 slides.

The printing fixture assembly is removably mounted on the frame assembly50, see FIG. 1. The printing plate 11 is held against the top edge ofthe sideplates 52 and 53 by capturing the chamfered front edge 12 of theprinting plate 11 under the chamfered rear edge 61 of a top plate 62which is attached transversely to the sideplates between the forwardends of the guide rods 57.

The rear edge 13 (FIG. 2) of the printing plate 11 is captured under thechamfered forward edge 63 (FIG. 5) of a retaining plate 64 which islocated transversely between the sideplates 52 and 53, immediatelyforward of the rear mountin g block 55 and clamped thereto by a knurledhead screw 66. The plates 11, 62 and 64 are arranged with their uppersurfaces coplanar so that the squeegee assembly 80 can slide smoothlyacross these surfaces in sequence. A pair of longitudinally extendingvertical guide plates 68-68 are mounted so as to extend above the sideplates 52 and 53 from the rear mounting block 55 forward to a point justbeyond the position of the squeegee assembly 80 when the carriageassembly 70 is in the loading position, so arranged that the squeegeeassembly fits slidably between the guide plates 68 as it moves acrossthe surfaces of plates 62, 11 and 64.

The carriage assembly 70 includes a pair of sidepieces 71- 71, slidablyfitted on the guide rods 57-57 and transversely connected by a bridgingplate 72 fastened to the sidepieces. A pair of brackets 73-73 is mountedon opposite sides of the bridging plate 72 to hold the squeegee assembly80 (FIG. 5). A transverse slot 75 in the overhanging portion of eachbracket 73, having a counterbore 74 (FIG. 5) at the inner end of theslot, provides a loose-fitting guide for the squeegee assembly 80. Apair of hook plates 76-76, rigidly connected by a transverse rod 77, ispivotally mounted on corresponding pins 78-78 which protrudehorizontally outward from each bracket 73, with the hook portionsadjacent the slots 75, see FIG. 5.

As shown in FIG. 6, the principal element of the squeegee assembly 80 isa stainless steel pot 81 open at its top and bottom, for containing thesupply of adhesive ink (not shown). At each end there extends arectangular cross section boss 83 from which a guide pin 84 extendshorizontally still further, for loose-fitting engagement in thecounterbores 74 (FIG. 5) and slots 75 (FIGS. 4 and 5) of the carriageassembly 70. A

pair of clamping plates 86-86 holds rubber strips 87-87 in a verticalposition along the front and rear edges of the bottom of the pot 81,parallel to the axis of the pin 84. When the squeegee assembly is inplace on the carriage assembly 70, the ends of the rubber strips 87press against the guide plates 68 68 (FIGS. 4 and 5) of the frameassembly, and the bottom edges of the rubber strips 87 press against topplate 62 (FIGS. 4 and 5), so that the ink supply in the pot cannot leakout. Felt pads 89 in recesses of the pot 81 between the rubber strips 87at each end protrude slightly so as to press against the frame guideplates 68, and thus prevent leakage of ink from between the rubberstrips 87. A removable cover plate 92 is held tightly to the open top ofthe pot 81 by a pair of knurled head screws 93 to prevent the ink supplyfrom drying.

As shown in FIG. 4, in the normal position the hook plates 76 of thecarriage assembly 70 bear downward on the guide pins 84 where theyextend through the slots 75, to hold the squeegee assembly in place. Thehook plates 76 can be rotated upward and forward from the guide pins 84so that the squeegee assembly can be removed.

As shown in FIGS. 4, 5 and 7, the plate fixture assembly (FIG. 5) isalso mounted on the carriage assembly 70. The fixture plate 101, whichis the principal element of this assembly 100, extends transverselybetween recesses in the top surfaces of the carriage sidepieces 71-71 towhich it is accurately located by dowel pins 102 (FIG. 5) and held byknurled head screws 103. A pair of longitudinal workpiece guides 104-104(FIG. 7) having an internal lower lip 105 is attached to the lowersurface of the fixture plate, so disposed that a workpiece 40 can beslid easily between the guides 104-104 with the bottom surface of theworkpiece resting on the lips 105-105. A pair ofpilot pins 107 and 108(FIG. 5), spring loaded by leaf springs 109, are slidably fitted inpilot holes in the fixture plate 101 to engage registration holes (notshown) in the workpiece 40, for alignment of the workpiece accurately tothe plate fixture assembly. To compensate for tolerance buildup betweenthe workpiece registration hole spacing and the fixture plate pilotholes, pilot pin 107 preferably operates in a longitudinally extendingslot which is a sliding fit transversely and a loose fit longitudinally.A guide step (not shown) is attached to the fixture plate so that theworkpiece can be inserted only to the point where the registration holesin the workpiece are under the pilot pins.

Openings 111 and 112 (FIG. 5) are provided in the fixture plate 101,arranged to expose the region of the workpiece in which are located theholes to be printed, so that the vacuum nozzle 200 (FIG. 4) can act onthose holes. A chamfered surface 113 (FIG. 7) in front lower edge of thefixture plate 101 immediately above the space between the longitudinalguides 104-104 provides a guide for the workpiece 40 into the openingbetween the plate 101 and the lips 105. A recess 114 (FIG. 5) isprovided in the fixture plate 101, and a tapering recess 115 (FIG. 7) inthe mounting block 54, so that an operator of the apparatus can grasp aworkpiece with his fin gers to withdraw it when the carriage assembly 70is in the loading position shown in FIGS. 1,4 and 5.

In normal operation, driving power is obtained from a continuouslyrotating electric motor with integral gearhead 117 (FIG. 5), connectedby a belt 118 to the shaft and intermittent clutch assembly 120. Asshown in FIG. 8, a shaft 121 is rotatably fitted in a bearing block 122which is fastened to the vertical sideplate 53 *(FIG. 5), so arrangedthat the axis of shaft 121 is transverse to the apparatus. A handwheel124 is fastened on one end of the shaft 121 to permit manual operationof the apparatus for inspection or setup. A sprocket 125, rotatablyfitted on the shaft 121 adjacent to the handwheel I24, engages the drivebelt 118 (FIG. 5). A key 126 is slidably fitted in the keyway 127 in theshaft 121 and handwheel 124, so that the key can be pressed fully inwardto engage a mating keyway 128 in the sprocket thereby locking thesprocket to the shaft 121. A ball plunger 129 mounted in the hub of thesprocket 125 engages a detent in the key 126 to hold the key in thekeyway 128. A stop 131 fastened to the handwheel 124,

and a shoulder 132 on the key 126 prevent the key 126 from being pulledout of the keyway 127.

A clutch-driving disc 134 having a plurality of holes 135 135 is rigidlymounted on the shaft 121 near the end opposite the handwheel 124, withthe axes of the holes 135 parallel to the axis of shaft 121 andequidistant therefrom. An intermittent clutch-driven plate 137 isrotatably mounted on the shaft 121 at the end opposite the handwheel 124and adjacent the clutch-driving disc 134, and is retained by a springclip 138 fitted in a groove at the end of the shaft 121. A fiat spring141 attached to the end of driven plate 137 bears against a clutch pin143 which fits slidably in hole 144 of the driven plate, the hole 144being parallel to the axis of shaft 121 and the same distance therefromas the holes 135. When the hole 144 is in line with one of the holes135, the spring 141 can urge the clutch pin 143 into engagement with thehole 135, to cause the driven plate 137 to rotate with the shaft 121. Aclutch release pin 146 extends radially from the clutch pin 143 andpasses slidably through an axial slot 147 in the driven plate, so thatmovement of the clutch release pin in a direction away from thehandwheel 124 overcomes the force exerted by the flat spring 141 andslides the clutch pin 143 out of engagement with the hole 135, to permitthe shaft 121 to rotate independently of the clutch-driven plate 137.

Principal details of the slide cam assembly 150 are shown in FIG. 4 andFIG. 7. A connecting rod 148 (FIG. 4) is rotatably attached to the endof clutch-driven plate 137 and pivotally connected to the cam plate 151.The cam plate is mounted to a backing plate 149 (FIG. 7) slidably fittedin a longitudinal groove in the frame assembly 50, so that rotation ofthe clutch-driven plate causes longitudinal reciprocating motion of thecam plate 151. The top edge of the cam plate 151 has sequentialhorizontal cam surfaces 152 and 154 (FIG. 4) connected by a slantsurface 153. These surfaces are engaged by the cam roller 38 of theprinting assembly 10, as shown in FIG. 2, and are so arranged that asthe roller follows the slant surface 153 upward the inking pins 33 areraised from the position for receiving ink to the position where theyapply ink to the holes of the workpiece, see FIGS. 3 and 3a. The loweredge of the cam plate 151 includes a downward protruding tooth having aleading edge 155 and a trailing edge 156 (FIG. 4) for engaging camroller 177.

A striker pin 158 projects transversely from the cam plate 151, sodisposed that it can engage a locating pin cam 161 which is rigidlyfastened to a transverse shaft 162 rotatably mounted to the frameassembly. A pair of locating pin-operating arms 164, rigidly fastened toshaft 162, extend longitudinally rearward from shaft 162 in anapproximately horizontal position. As the cam plate 151 advances, andjust before the cam roller 38 engages the cam surface 152, the strikerpin 158 contacts the bottom edge of cam 161 to rotate cam 161 and shaft162 slightly. A connecting pin 167 extends transversely from the lowerend of each of a pair of vertical locating pins 168 through acorresponding longitudinal slot 165 near the extreme end of each arm164, so that rotation of the operating arms 164 causes vertical motionof the locating pins 168-168.

Each locating pin 168 is slidably fitted in a vertical hole 169 of abracket 172, the brackets being mounted opposite each other on the outersurfaces of the sideplates 52 and 53 of the frame assembly. The brackets172-172 are arranged such that, when the carriage assembly has beenmoved to the printing position with the holes in the workpiecepositioned approximately above the corresponding holes 14-14 in theprinting plate 11, the locating pins 168-168 are under and approximatelyin line with mating close-fitting holes (not shown) in the underside ofthe carriage sidepieces 7l-71. The upper ends of the locating pins168-168 are pointed so that, as the pins are raised by rotation of theoperating arms 164, the carriage assembly 70 may be moved longitudinallyas required to permit the locating pins to enter the holes in thesidepieces 71-71, thus aligning the carriage assembly 70 and workpiece40 precisely above the printing plate 11. A pair of springs 173 (FIG. 4)withdraws the pins 168 to a mechanical stop (not shown) when the strikerpin 158 is not engaging cam 161.

A shaft 174 is rotatably mounted in the sideplates 52 and 53 with itsaxis transverse and below the slide cam assembly 150. A pair of sectorplates 175, rigidly fixed to the shaft 174 near its center, support camroller 176 and 177 between the sector plates with the axes of the camrollers parallel to and equidistant from the axis of shaft 174. Inoperation, the leading edge (FIG. 4) of the tooth on the cam plate 151engages the roller 176 as the slide cam assembly 150 moves rear ward, torotate the sector plates from the loading position to the printingposition, and the trailing edge 156 of the tooth engages the roller 177as the slide cam assembly returns to the loading position, to rotate thesector plates 175 back to the loading position. A pair of pivot arms178-178, rigidly attached to the ends of the shaft 174 outside thesideplates 52 and 53, extend upwardly in the same radial direction asthe sector plates 175. The upper end of each pivot arm 178 is coupled tothe corresponding sidepiece 71 of the carriage assembly 70 by aconnecting link 179 (FIG. 7) pivotally attached at its correspondingends to the pivot arm and sidepiece, so that rotary motion of the sectorplates 175 will cause translation of the carriage assembly along theguide rods 57.

The intermittent clutch assembly 120 (FIG. 4) is controlled by a clutchtripper assembly 180 mounted below the clutch assembly 120 betweensideplates 52 and 53. A clutch release cam 181, pivotally mounted on apin 183 having its axis parallel to the shaft 121, is located adjacentto the clutch-driven plate 137. With the cam 181 in its normal positionthe cam surface is in helical relation to the axis of shaft 121 sodisposed that, at the point in driven plate 137 rotation where thecarriage assembly has nearly returned to the loading position, theclutch release pin 146 engages the surface of cam 181. As the drivenplate 137 rotates further, the clutch release pin follows the helicalpath away from the driving disc 134, sliding the clutch pin 143 out ofthe hole 135 so that the driven plate 137 stops rotating, see FIG. 4.

A pin 185 extending transversely from the cam 181 extends into a slot186 in a release lever 187, the lever being fastened rigidly on atransverse shaft 189 mounted rotatably between the sideplates 52 and 53and having an end protruding through plate 52. Rotation of the lever 187and shaft 189 causes the cam 181 to pivot about the pin 183 away fromthe clutch driven plate 137. Such motion disengages the clutch releasepin 146 form the cam surface, thereby permitting the flat spring 141 topush the clutch pin 143 into one of the holes 135 in the driving disc134, see FIG. 8. For manual operation of the clutch, a knob 191 isprovided on the exposed end of the shaft 189. Automatic operation isobtained through a solenoid 193 which is mounted on base plate 51 andmechanically connected to the release lever 187 by pivotally attachedconnecting link 194, so that energizing the solenoid causes the lever187 to rotate. A spring 196 is connected between the lever 187 and thesolenoid end of the link 194 to return the lever and solenoid to thedeenergized position.

A nozzle 200 (FIG. 4) connected to a vacuum valve and source (not shown)is mounted over the plate fixture assembly 100 (FIG. 4) by a bracket(not shown), so arranged that when the carriage assembly is in theloading position the openings 111 and 112 (FIG. 5) are under the nozzle200. A camoperated switch (not shown) is mounted in such a way that abrief switch closure is obtained just before the clutch-driven plate 137has reached the loading position, at which the plate stops betweenoperating cycles of the apparatus. The switch closure actuates thevacuum valve, so that a pulse of air preferably less than 1 second induration is drawn upward through the holes of the workpiece.

A control box (not shown) is mounted in any position convenient for theoperator, and typically includes a fuse, a switch with indicating pilotlight for the electrical supply, and a momentary contact switch forenergizing the solenoid.

With reference to the foregoing description, the operation of thisembodiment of the invention is as follows:

A workpiece, having a pattern of holes to which adhesive ink is to beapplied, is inserted by an operator into the opening in the platefixture assembly 100 so that the workpiece rests on the lips 105, withthe side to be imprinted facing down, and is pushed inward until it hitsthe guide stop and is held in place by the pilot pins 107 and 108. Theoperator then presses the switch which controls the solenoid 193.

Viewed from the direction of FIG. 4, operation of the solenoid rotatesthe release lever 187 clockwise, pulling the clutch release cam 181 downand thus releasing the clutch release pin 146. The spring 141 pushes theclutch pin 143 into one of the holes 135 in the continually rotatingdisc 134, so that the clutch-driven plate 137 begins to rotateclockwise. As the slide cam assembly 150 is advanced to the right, theleading edge 155 engages the cam roller 176 and rotates the sectorplates 175 clockwise until the tooth-leading edge can pass over theroller 176. Rotation of the pivot arms 178 pulls the carriage 70 andsqueegee assembly 80 into the printing position above the printingfixture assembly 10, spreading the ink 42 from the squeegee assemblyinto the holes 14 of the printing plate 11 as the carriage moves. As theslide cam assembly continues to advance, the striker pin 158 engages cam161. This rotates the shaft 162 and locating pin arms 164 slightlycounterclockwise, and raises the locating pins 168 so that they engagethe snug-fitting holes in the carriage sidepieces 71, aligning andlocking the carriage in position. As the slide cam assembly advances toits extreme position, the cam surfaces 153 and then 154 pass under thecam roller 38, forcing the plates 21 and 27 upward until the pins 33contact the holes in the workpiece, as shown in FIGS. 2 and 3a.

As the clutch-driven plate continues to rotate, the slide cam assembly150 is pulled back to its starting position, and the various othermechanisms return to their start positions in reverse order. The springs25 return the pins 33 and plates 21 and 27 downward, and then thesprings 173 withdraw the locating pins 168 from the carriage sidepieces71. Finally, the cam plate tooth railing edge 156 engages the roller 177and returns the carriage to its starting position, so that the platefixture assembly 100 is under the vacuum nozzle 200. The cam-operatedswitch actuates the vacuum valve, so that the resulting pulse of airsucks the ink upward in the holes to obtain a smooth coating.

Since the solenoid 193 is operated only momentarily, the clutch releasecam 18] returns to its normal position while the driven plate 137 isrotating, and the clutch pin 143 is then withdrawn from the driving disc134 as the driven plate 137 completes one revolution. This finishes acomplete operating cycle. The operator can now grasp the workpiece andwithdraw it from the carriage, and proceed to repeat the operation withanother workpiece.

As can be seen from the detailed description above, a fea ture of thisembodiment of the invention is the grouping of parts, which are peculiarto one pattern of holes or configuration of workpiece, into twoassemblies which are easily removed and replaced: the plate fixtureassembly and the printing fixture assembly. This feature providesmaximum utility of the basic apparatus with a minimum expenditure forcapital equipment and setup time.

As will be appreciated by one skilled in the art, many variations in theapparatus disclosed can be made without departing from the spirit of theinvention. For example, the transfer pins 33-33 may be held stationaryand the workpiece 40 and printing plate 11 displaced towards the pins totransfer material from the plate to the workpiece.

What is claimed is:

1. An apparatus for applying catalytic ink to the periphery and walls ofholes formed in a predetermined pattern in a printed wiring board, saidapparatus comprising:

a reciprocable carriage for receiving the printed wiring board;

a perforated plate having holes formed therein in a patterncorresponding to the pattern of the holes in said printed wiring board;

applicator means for introducing the catalytic ink into the holesformedjn said erforated late; means for moving sal reciproca le carriageto a position adjacent said perforated plate;

positioning means responsive to movement to said adjacent position foraccurately positioning said reciprocable carriage so that said holes insaid printed wiring board are in registration with the correspondingholes in said perforated plate;

a vertically movable member;

a plurality of transfer pins mounted vertically in said verticallymovable member and aligned with said holes in said perforated plate; and

lifting means for raising the vertically movable member so that theupper ends of said plurality of pins move through the holes of saidperforated plate to pick up the catalytic ink introduced therein andapply the ink to the periphery and walls of said holes in said printedwiring board.

2. The apparatus claimed in claim 1; comprising in addition:

vacuum means located above the reciprocable carriage for brieflyapplying a partial vacuum to produce a pulse of airflow through saidholes in said printed wiring board so that said catalytic ink spreadssmoothly about and within said holes in said printed wiring board.

3. The apparatus claimed in claim 1 wherein said applicator meanscomprises means for applying catalytic ink across the entire perforatedplate while said reciprocable carriage is being moved to said adjacentposition, comprising in addition:

squeegee means for removing said catalytic ink from said perforatedplate while leaving a predetermined amount of said catalytic ink in saidholes in said perforated plate.

4. The apparatus claimed in claim 3; comprising in addition:

vacuum means located above the reciprocable carriage for brieflyapplying a partial vacuum to produce a pulse of airflow through saidholes in said printed wiring board so that said catalytic ink spreadssmoothly about and within said holes in said printed wiring board.

5. The apparatus claimed in claim 1, wherein said plurality of pins aremounted such that their upper ends project partly into but below the topof the corresponding holes in said perforated plate when said verticallymovable member is at its lowest position to define a cavity forreceiving a predetermined volume of said material.

6. The apparatus claimed in claim 5; comprising in addition:

vacuum means located above the reciprocable carriage for brieflyapplying a partial vacuum to produce a pulse of airflow through saidholes in said printed wiring board so that said catalytic ink spreadssmoothly about and within said holes in said printed wiring board.

1. An apparatus for applying catalytic ink to the periphery and walls ofholes formed in a predetermined pattern in a printed wiring board, saidapparatus comprising: a reciprocable carriage for receiving the printedwiring board; a perforated plate having holes formed therein in apattern corresponding to the pattern of the holes in said printed wiringboard; applicator means for introducing the catalytic ink into the holesformed in said perforated plate; means for moving said reciprocablecarriage to a position adjacent said perforated plate; positioning meansresponsive to movement to said adjacent position for accuratelypositioning said reciprocable carriage so that said holes in saidprinted wiring board are in registration with the corresponding holes insaid perforated plate; a vertically movable member; a plurality oftransfer pins mounted vertically in said vertically movable member andaligned with said holes in said perforated plate; and lifting means forraising the vertically movable member so that the upper ends of saidplurality of pins move through the holes of said perforated plate topick up the catalytic ink introduced therein and apply the ink to theperiphery and walls of said holes in said printed wiring board.
 2. Theapparatus claimed in claim 1; comprising in addition: vacuum meanslocated above the reciprocable carriage for briefly applying a partialvacuum to produce a pulse of airflow through said holes in said printedwiring board so that said catalytic ink spreads smoothly about andwithin said holes in said printed wiring board.
 3. The apparatus claimedin claim 1 wherein said applicator means comprises means for applyingcatalytic ink across the entire perforated plate while said reciprocablecarriage is being moved to said adjacent position, comprising inaddition: squeegee means for removing said catalytic ink from saidperforated plate while leaving a predetermined amoUnt of said catalyticink in said holes in said perforated plate.
 4. The apparatus claimed inclaim 3; comprising in addition: vacuum means located above thereciprocable carriage for briefly applying a partial vacuum to produce apulse of airflow through said holes in said printed wiring board so thatsaid catalytic ink spreads smoothly about and within said holes in saidprinted wiring board.
 5. The apparatus claimed in claim 1, wherein saidplurality of pins are mounted such that their upper ends project partlyinto but below the top of the corresponding holes in said perforatedplate when said vertically movable member is at its lowest position todefine a cavity for receiving a predetermined volume of said material.6. The apparatus claimed in claim 5; comprising in addition: vacuummeans located above the reciprocable carriage for briefly applying apartial vacuum to produce a pulse of airflow through said holes in saidprinted wiring board so that said catalytic ink spreads smoothly aboutand within said holes in said printed wiring board.